愚人节AprilFool’sDayApril1Insixteenth-centuryFrance,thestartofthenewyearwasobservedonAprilfirst.Itwascelebratedinmuchthesamewayasitistodaywithpartiesanddancingintothelatehoursofthenight.Thenin1562,Pope（罗马教皇）GregoryintroducedanewcalendarfortheChristianworld,andthenewyearfellonJanuaryfirst.Thereweresomepeople,however,whohadn'theardordidn'tbelievethechangeinthedate,sotheycontinuedtocelebrateNewYear'sDayonAprilfirst.Othersplayedtricksonthemandcalledthem"Aprilfools."Theysentthemona"fool'serrand"ortriedtomakethembelievethatsomethingfalsewastrue.InFrancetoday,Aprilfirstiscalled"Poissond'Avril."Frenchchildrenfooltheirfriendsbytapingapaperfishtotheirfriends'backs.Whenthe"youngfool"discoversthistrick,theprankster（爱开玩笑的人）yells"Poissond'Avril!"(AprilFish!)TodayAmericansplaysmalltricksonfriendsandstrangersalikeonthefirstofApril.OnecommontrickonAprilFool'sDay,orAllFool'sDay,ispointingdowntoafriend'sshoeandsaying,"Yourshoelaceisuntied."Teachersinthenineteenthcenturyusedtosaytopupils,"Look!Aflockofgeese!"andpointup.Schoolchildrenmighttellaclassmatethatschoolhasbeencanceled.Whateverthetrick,iftheinnocentvictimfallsforthejokethepranksteryells,"AprilFool!"The"fools'errands"weplayonpeoplearepracticaljokes.Puttingsaltinthesugarbowlforthenextpersonisnotanicetricktoplayonastranger.Collegestudentssettheirclocksanhourbehind,sotheirroommatesshowuptothewrongclass-ornotatall.Somepracticaljokesarekeptupthewholedaybeforethevictimrealizeswhatdayitis.MostAprilFooljokesareingoodfunandnotmeanttoharmanyone.ThemostcleverAprilFooljokeistheonewhereeveryonelaughs,especiallythepersonuponwhomthejokeisplayed."ThefirstofAprilisthedaywerememberwhatwearetheother364daysoftheyear."----AmericanhumoristMarkTwain
